中文摘要：

针对聚乙二醇（PEG）合成反应器中环氧乙烷（EO）溶解度测量困难问题，提出一种基于UNIFAC基团贡献法的理论估算方法。将不同相对分子质量的PEG混合物用平均EO加成数n（EO）表达，建立了EO—PEG体系的基团划分方法和UNIFAC模型，通过计算取得了／Z（EO）在0—40范围内EO—PEG体系的汽液平衡数据，并与实验数据进行了比较。结果表明：随着EO平均加成数的增大，EO在液相中的活度系数持续减小，EO溶解度持续增大；当n（EO）〈8时，基团分子间相互作用对EO活度系数的贡献较大，而当／2（EO）〉15时，体系的非理想性主要由分子的大小和形状差异引起，此条件下基团问相互作用对活度系数的影响可以忽略。

英文摘要：

A theoretical method based on UNIFAC group contribution model was proposed for predicting the vapor- liquid equilibria of ethylene oxide （EO）-ployethylene glycols （PEG） systems, aiming at overcoming the difficulty of EO solubility measurement in industrial ethoxylation reactor. The method of group division in EO-PEG systems and the parameters of UNIFAC model were established by taking PEG mixtures with different relative molecular mass as a pseudo-component with an averaged numbers of EO adducts n （EO）. On that basis, the vapor-liquid equilibria data of EO-PEG system at different n（EO） ranging from 0 to 40 were obtained through calculations and compared with the experimental results. The resuXts show that EO activity coefficient in liquid phase reduces constantly with the increase of n（EO） , which corresponds to the solubility of EO in PEG increased constantly. The analysis of EO solubility change rules in PEG was also carried out, and the result reveals that when n（EO） 〈 8, the interaction of groups plays a major contribution to the activity coefficients of EO; when n（EO） 〉 15, the non- ideality of system is resulted from the differences of size and shape of the molecules, which means the effect of the interaction of group on activity coefficient can be negligible.